FLOOD RISK, COASTAL MEGACITIES, AND URBAN POOR: ASSESSING THE FUTURE URBAN FLOOD RISK IN THE H/E WARD OF MUMBAI

Abstract

In India, Mumbai city is highly vulnerable to the threats posed by climate change, such as sealevel rise, storm, and floods. The vulnerability of the city was demonstrated on the 26 July 2005 when thousands of houses were submerged in the water, and assets worth billions of rupees were damaged. The flood severely impacted the residents in informal settlements known as slums, which incurred substantial financial losses. With the increasing vulnerability of coastal megacities to urban floods, there is a need for an effective risk assessment and Adaptation Planning. Hence this study aims to assess the current amd future Flood Risk faced by the H/E Ward (study area) of Mumbai. The flood risk assessment is performed using the standard catastrophe Risk modeling, which combines Hazard, exposure, and vulnerability. Various data sources such as Historical rainfall data, Elevation Data, Soil Database, Landsat Imagery, and census data were collected from multiple online sources to achieve this objective. The data processing is done using GIS, Hydrological and Hydraulic Processes. As the H/E ward lies in the Mithi River catchment area, we processed the DEM and used the SCS-Curve Number and kinematic routing method to generate the peak discharge at the River Sub basins in HEC-HMS software. The River geometry is prepared in HEC-RAS software, and Flood Hazard Maps were prepared. The current & future Risk analysis shows an increase in the inundation extent for the 100 year return period in the H/E Ward, which highlights that there would be an increase in the total affected Population and losses incurred by them. The study also highlights that the people's adaptive capacity is deficient. Most of the affected Population are poor people, employed in menial jobs, chosen to stay in the riskier site because of proximity to work. Hence this study highlights an urgent need for an effective Risk Management and Adaptation planning in the H/E ward of Mumbai.